D-amino acids are important as intermediates for a variety of pesticides, antibiotics and medicinal drugs. Many studies have been studied for their synthesis. To date, a DL-amino acid can be resolved by a physiochemical, chemical or enzymatic method, among which an enzymatic method has been considered to be most convenient and advantageous. In a known example of an enzymatic method, an N-acetyl-DL-amino acid is hydrolyzed using a D-aminoacylase to directly produce a corresponding D-amino acid.
Known sources of D-aminoacylases include microorganism belonging to bacteria, actinomyces and mold such as Pseudomonas (Japanese Patent Publication (JP-B) No. 60-31477), Streptomyses (JP-B 53-36035), Alcaligenes (JP-B 07-83711), Rhodococcus, Pimelobacter (Japanese Patent Laid-Open (JP-A) No. 06-227789), Arthrobacter, Corynebacterium, Erwinia, Escherichia, Flavobacterium, Norcadia, Protaminobacter, Xanthomonas (Japanese Patent Laid-Open (JP-A) No. 11-113592), Amycolatopsis (JP-A 11-98982), Sebekia (JP-A 11-318442), Hypomyces, Fusarium, Auricularia, Pythium, Menisporosis (JP-A 12-41684). There has been reported production of a D-amino acid using the action of a D-aminoacylase derived from any of these sources on an N-acylamino acid.
These D-aminoacylases, however, exhibit insufficient activity at a useful substrate concentration, and thus an industrially available D-aminoacylase has been needed. In particular, in hydrolysis of N-acetyl-D-tryptophan, these enzymes exhibit inadequate activity at a useful concentration. They cannot be, therefore, called industrially satisfactory enzymes. Recently, Tokuyama (JP-A 13-275688) and Taylor (Chirotech Technology Limited, WO 00/23598) have disclosed, as a D-aminoacylase which acts on N-acetyl-D-tryptophan to produce D-tryptophan, D-aminoacylases derived from Hypomyces and from Alcaligenes, respectively. Either of these D-aminoacylases which can hydrolyze N-acetyl-D-tryptophan only up to 10 g/L, cannot be regarded to be an enzyme which can catalyze the reaction at a useful concentration.
D-amino acids are important as starting materials for medical drugs, and thus there have been needed to develop a process for production thereof at a lower cost. There have been known no D-aminoacylases which can effectively catalyze a D-amino acid.